No start; GP + GPC issue?

[School_Bus]

This is my first post, but ive been reading as much as i can for my issues before posting.

1986 Ford 6.9 IDI

Ive owned it for about 3 months now. The first two months the thing drove fine. Then a hard start issue creeped up, then it became a no start.

First thing i checked was the glow plugs. 6 of the 8 tested as bad using a check light.

I replaced the 6 bad GB's with Motorcraft GPs. After the change out, the truck started just fine and ran fine for about a week or so.

Then, snow came this weekend and dropped 30" of snow, I tried to start it on Thursday night before the storm and it wont start again.

It cranks and cranks and cranks. White smoke comes out of the exhaust (which would lead me to believe that the glow plugs arent heating up). The Glow Plug light will light for about 10 seconds and i can hear the relay click. Still no start. After the first start cycle, if i try to cycle the Glow plugs again they only light for a second then click off. Ive checked the fuel shrader valve during cranking and ill will get a cycle of Steady flow of diesel for second or two, then nothing, then steady flow of diesel, then nothing, diesel, nothing, diesel, nothing.

Theres too much snow on my truck now to check it, so im asking this before i do later this week.

Can a bad glow plug relay or glow plug controller be causing this isssue?
Could a bad glow plug relay or glow plug controller fry my new glow plugs?


I have two things planned for this weekend and next. This weekend i plan to bypass the GPR and GPC using a standard 12v starter relay and a push button switch. Next weekend i plan to replace the mechanical fuel pump with an electrical pump system. I already have the parts for the GP bypass and i ordered the Transicold pump today.

Any help would be appreciated, thanks.

 

[crash-harris]

Replace the other 2 GP's to match the rest. While your in there, check your connectors and wiring (GP harness). Others here will be able to be more helpful on the controller. Luckily I haven't had this issue so I lack the experience.

 

[riphip]

On the 86, bypass the water separator on driver side if it is still there. Common cause of air intrusion.
Also update the old controller to the 7.3 controller if not already done. You'll love how well it works.

 

[School_Bus]

I have my water separator replaced by the AG mod kit that puts the NAPA gold filter on instead.

 

[Lifted Mudder]

Does it start up fine if you plug it in?

 

[OLDBULL8]

There is nothing wrong with the GP controller if it cycled for 10 seconds. Replace the other two GP's. You have the ZD1 GP's I take it, make sure the spade connectors are tight and the connection on the relay is not loose or corroded.

Do you have the controller that screws into the head or the one that looks like this ?

 

[School_Bus]

Does it start up fine if you plug it in?

This truck did not come with a block heater.

 

[School_Bus]

There is nothing wrong with the GP controller if it cycled for 10 seconds. Replace the other two GP's. You have the ZD1 GP's I take it, make sure the spade connectors are tight and the connection on the relay is not loose or corroded.

Do you have the controller that screws into the head or the one that looks like this ?

I will check this afternoon. I know that the ones i replaced were replaced with the correct Motorcraft GP's. Uknown what was i nthere, i guess il lreplace the other two GP's this weekend.

 

[OLDBULL8]

This truck did not come with a block heater

With your user name it kind of throws a guy off.

Is this a school bus or a truck, both can be on a F350 frame.

All diesel "trucks" came with a block heater AFAIK. A school bus could be an exception. You would have to look on the pass side behind the starter to see if it has just a freeze plug or a thing to plug in a cord. The cord from there is usually hidden behind the bumper or grill.

It's possible that the block heater went bad and was replaced with a freeze plug.

 

[bbjordan]

Check connector

Check the yellow/orange wires that go to the Glow Plug Relay at the connector on the passenger side. They may be corroded or melted. A common fix is to solder them together, or run a dedicated wire(s) to the GPR bypassing the connector.

I wouldn't mess with the Fuel/Water at this time. If you have white smoke, you are getting fuel to the cylinders.

You could try disconnecting the GPR so there is no power to the GPs, and use ether/starting fluid. Try a 1 to 2 second spray into the air intake and it should fire up.

The pic is from a '91, but you get the idea...

 

[School_Bus]

Ok, here is an update.

I checked the BRAND NEW MOTOCRAFT ZD-1-A glow plugs i installed two weeks ago and they are all dead now! They fail the check light method and the resistance test with a multimeter.

To refresh, i checked all 8 of them three weeks ago and 6 checked out dead. So i replaced the 6 dead ones with the motorcraft ones. The ones that came out of the truck were champion brand. Today i checked that all GP's are receiving 12 volts when the key to turned on and go to 0 volts when the GP relay clicks off. Somewhere between 12.01-12.03 volts DC. Im going to the store to buy 6 more motorcraft brand GP's now to install, but im not going to run the truck until i can get a specific answer as to what is killing these new GP's. Still getting plenty of diesel out of the fuel shader valve and plenty of white smoke out of the exhaust.

Could the fact that 6 of the GP's were different than the other two and fried them due to maybe a difference in resistance?
Could the GPC or GPR be frying them for whatever reason?

My theory is that the difference in the GP's was what caused them to die. I think i remember somewhere that if one GP fails, it will take out the other seven within a short period of time. So maybe the two i didnt replace were near death and when they finally did they took out the other 6. But im hoping someone with more experience with them can confirm this for me

Here is a pic of the GPC and GPR setup i have on the truck. Seems all factory. Also, this is not a school bus, ignore moy name, This is a standard cab, '86, F350 4WD.

 

[DaveBen]

All of your connectors are getting corroded. Clean ALL of them and brush on some dielectrical grease to keep them clean.

Dave

 

[bbjordan]

The old 6.9 GP controllers are notorious for failing in the on position, which will burn up your GPs. Since you have the parts for the GP relay bypass, put it in and disconnect the GP controller. (You have to squeeze the sides of the connector to pull it off)

 

[OLDBULL8]

I magnified your pic 250+, still can't see which GP controller you have. The relay appears to have a black and a red wires to it, black should be grounding, red should be trigger.
If the controller is the one that screws into the head, they can become defective and keep the relay energized, that would burn out the GP's. You have to answer the questions.

Since it appears you have a stand alone relay, hard to tell what you have.

Anyhow, here is both circuits. Also a better pic of the later GPC.

 

[OLDBULL8]

@bbjordan
Since he has a stand alone relay, and from the pic of the 83 circuit, he does have the the screwed in the head controller. Your right about them shorting out and holding the relay energized, that'll burn out the GP's for sure.